I’d bet this has more to do with liability than anything else. If a cyclist falls due to the tracks, he’ll have a harder time proving that the crossing was faulty and hazardous. He was warned, after all.

It’s for their own good … so they can’t be sued when some doofus bites it on the tracks.

Up here in King County, WA, a fellow crashed pretty hard on a pothole and was very seriously injured. Since the route was marked as a bicycle route on the County Bike Map, his family successfully sued the county for millions. Now there’s a disclaimer on the map stating that they make no guarantees for the condition of the road, even if it is marked as a good bicycle route.